Multiple sclerosis and endometriosis in women both used to be diagnosed as hysteria. The same could be happening with 'Havana syndrome.'
Sociologists know what conditions make it more likely a mass delusion will take hold and spread through a group – whether adherence to a fashion fad or belief in a doomsday cult.
Random clown sightings don't make everyone laugh. A psychologist who has studied creepiness explains why clowns are especially adept at making us squirm.